We present galactic spectroscopic data from a pencil beam of 10.75×7.5 centered on the X-ray cluster RXJ0054.0-2823 at z=0.29.We study the spectral evolution of galaxies from z=1 down to the cluster redshift in a magnitude-limited sample at R≤23,for which the statistical properties of the sample are well understood.We divide emission-line galaxies into star-forming galaxies,Low Ionization Nuclear Emission line Regions(LINERs) ,and Seyferts by using emission-line ratios of[OII],Hβ,and[OIII],and derive stellar fractions from population synthesis models. We focus our analysis on absorption and low-ionization galaxies.For absorption-line galaxies,we recover the well-known result that these galaxies have had no detectable evolution since z～0.6-0.7,but we also find that in the range z=0.65-1,at least 50% of the stars in bright absorption systems are younger than 2.5 Gyr.Faint absorption-line galaxies in the cluster at z=0.29 also had significant star formation during the previous 2-3 Gyr,but their brighter counterparts seem to be only composed of old stars.At z～0.8,our dynamically young cluster had a truncated red-sequence.This result seems to be consistent with a scenario where the final assembly of E/S0 took place at z<1.In the volume-limited range 0.35≤z≤0.65,we find that 23% of the early-type galaxies have LINER-like spectra with Hβin absorption and have a significant component of A stars.The vast majority of LINERs in our sample have significant populations of young and intermediate-aged stars and are thus not related to AGNs,but to the population of'retired galaxies'recently identified by Cid Fernandes et al.in the Sloan Digital Sky Survey(SDSS) .Early-type LINERs with various fractions of A stars and E+A galaxies appear to play an important role in the formation of the red sequence.
The light curve data from 1894 to 2008 are compiled for the BL Lacertae object OJ 287 from the available literature.Periodicity analysis methods(the Discrete Correlation Function-DCF,the Jurkevich method,the power spectral(Fourier) analysis,and the CLEANest method) are performed to search for possible periodicites in the light curve of OJ 287.Significance levels are given for the possible periods.The analysis results confirm the existence of the 12.2±0.6 yr time scale and show a hint of a～53 yr time scale.The 12.2±0.6 yr period is used as the orbital period to investigate the supermassive binary black hole system parameters.
Jun-Hui FanYi LiuBo-Chun QianJun TaoZhi-Qiang ShenJiang-Shui ZhangYong HuangJin Wang
Using the database of the University of Michigan Radio Astronomy Observatory (UMRAO) at three radio frequencies (4.8,8 and 14.5GHz),we determined the short-term variability timescales for 166 radio sources. The timescales are 0.15d (2007+777) to 176.17d (0528–250) with an average timescale of △tobs = 17.1 ± 16.5d for the whole sample. The timescales are used to calculate the brightness temperatures, TB. The value of log TB is in the range of log TB = 10.47 to 19.06K. In addition,we also estimated the boosting factor for the sources. The correlation between the polarization and the Doppler factor is also discussed.
Warm absorption is a common phenomenon in Seyfert 1s and quasars, but is rare in Seyfert 2s. We report the detection of warm absorbers with high energy resolution in the Seyfert 2 galaxy IRAS 18325-5926 for the first time with Chandra HETGS spectra. An intrinsic absorbing line system with an outflow velocity ～ 400 km s-1 was found, which is contributed by two warm absorbers with FWHM of 570 km s-1 and 1360 km s-1, respectively. The two absorbers were adjacent, and moving transversely across our line of sight. We constrained the distance between the center and the absorbers to be a small value, suggesting that the absorbers may originate from the highly ionized accretion disk wind ejected five years ago. The perspective of this type 2 Seyfert provides the best situation in which to investigate the vertical part of the funnel-like outflows. Another weak absorbing line system with zero redshift was also detected, which could be due to Galactic absorption with very high temperature or an intrinsic outflow with a very high velocity ～ 6000 km s-1.
The correlations between broad-line emission,polarization,and core-dominance parameters are investigated for a sample of 148 blazars(BL Lacertae objects-BLs and flat spectrum radio quasars-FSRQs). An anti-correlation between the broad-line luminosity and the linear polarization is found. The broad-line and polarization relation can be explained by using a relativistic beaming model,which perhaps suggests that BL Lacs and FSRQs are a single class. We also investigated the relation between the ratio of the broad-line luminosity to the Eddington luminosity and linear polarization,and that between the ratio of the broad-line luminosity to the Eddington luminosity and the core-dominance parameter.
YANG JiangHe 1,2 ,FAN JunHui 2,3 & YANG RuShu 1 1 Department of Physics and Electronics Science,Hunan University of Arts and Science,Changde 415000,China
Observations suggest that γ-ray loud blazars are strongly beamed. The Fermi mission has detected many of blazars, which provide us with a good oppor- tunity to investigate the emission mechanism and the beaming effect in the γ-ray re- gion. We compiled the X-ray observations for 138 Fermi blazars (54 flat spectrum radio quasars, 36 low-peaked BL Lacertae objects, and 48 high-peaked BL Lacertae objects) and calculated their Doppler factors, δγ . It is interesting that the calculated Doppler factors, δγ , are strongly correlated with the γ-ray luminosity.
